TITLE: GCN CIRCULAR NUMBER: 12763 SUBJECT: GRB111228A: TNG spectroscopy analysis DATE: 11/12/29 12:36:46 GMT FROM: Dino Fugazza at INAF-OAB E. Palazzi (INAF-IASFBo), D. Fugazza (INAF-OAB), S. Piranomonte (INAF-OAR) on behalf of a larger collaboration report: The afterglow of GRB 111228A (Ukwatta et al. GCN 12737) was observed with the DOLORES instrument mounted at the Telescopio Nazionale Galileo on La Palma, Canary Islands. Starting on December 29.1200 (~11 hour after the burst), a series of three spectra of 1800s each were secured with LR-B grism (range 3500-8000 Angstroms). Preliminary reduction of the spectra reveals absorption features that we identify with the following absorption lines: Lines ID Lambda_observed (Angstroms) FeII_2344.21 4019.83 FeII_2374.46 4073.40 FeII_2382.76 4088.32 FeII_2585.65 4436.05 FeII_2600.17 4460.64 MgII_2795.50 4795.65 MgII_2802.70 4808.58 MgI_2852.96 4891.53 CaII_3933.68 6756.61 CaII_3968.49 6807.44 The derived redshift is z=0.7156 ± 0.0005 which confirms the results obatined by Dittman et al. (GCN 12759) and Cucchiara et al (GCN 12761). In addition to the GRB afterglow we observed the SDSS galaxy reported by Guver (GCN 12741). We detect many emission lines (OII_3726+3728, Hbeta, OIII_4958, OIII_5006, Halpha) at a common redshift of 0.218 ± 0.001 which is in agreement with the reported photometric redshift. This galaxy is therefore not related to the GRB. We acknowledge the excellent support from the TNG staff, in particular Walter Boschin and Gianni Tessicini [GCN OPS NOTE(22jan12): Per author's request, the affilation was changed from "U.Milano-Bicocca,INAF/Brera" to "INAF-OAB".]